Chapter 11: Part 4 What Starts a Meal

Question 1

what are signals from the environment?

Answer 1

from an evolutionary standpoint it makes sense to eat as much as possible and the fattiest food possible because you should eat when food is available. For our ancestors, who perhaps did not have as much food it was advantageous to eat when food was available. The book talks about the time it takes for food to leave the stomach would suggest we eat three meals a day. It is also believed that the sight of a plate of food, or the smell of food cooking or other people eating also signals hunger.

Question 2

what are signals from the stomach?

Answer 2

ghrelin is a peptide hormone that is released by the gastrointestinal system when someone is hungry. It can even stimulate thoughts about food.

Question 3

what about metabolic signals?

Answer 3

when we normally eat we are not actually hungry physiologically because we just ate a couple of hours prior to the current meal. During the absorptive phase of metabolism, we live on the food that is being absorbed from the digestive tract and after we start to dive into our nutrient reservoirs. A fall in blood glucose level (called hypoglycemia) is a stimulus for hunger.

Question 4

what is hypoglycemia?

Answer 4

a fall in blood glucose level

Question 5

what is glucodeprivation?

Answer 5

depriving cells of glucose

Question 6

what is lipoprivation?

Answer 6

depriving cells of lipids

Question 7

where are the detectors that monitor the level of metabolic fuels?

Answer 7

one set located in the brain and another set in the liver

Question 8

what do the detectors in the brain do?

Answer 8

contains detectors that monitor the availability of glucose (its only fuel) inside the blood–brain barrier

Question 9

what do the detectors in the liver do?

Answer 9

liver contains detectors that monitor the availability of nutrients (glucose and fatty acids) outside the blood–brain barrier.